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can anyone tell me how this is working

Posted: Thu Nov 14, 2013 7:05 pm
by cutedrummerboy
i am new to routeros recently i got a 2nd hand rb411 with a db2 networks radio card. in this page they assign a ip range to all the computer and the rb also. can anyone explain me what is happening in this case?

Link: http://wiki.ctwug.za.net/PTP_Link

Re: can anyone tell me how this is working

Posted: Fri Nov 15, 2013 10:29 am
by cutedrummerboy
ok, after a night of sleepless research i learn all the thing but one described it that link.

what i understand

1. they just simply assign a address from that given block to the internal interface of rb and made it the gateway for other clients of the same ip range in internal network.

2. they fixed a route that all traffic generated from internal network will be routed to the external network gateway.

so simple...

but i cannot understand

1. they put the same ip of internal network interface at the external network interface but without range

2. they put the gateway ip of external network as network and broadcast address of external network interface

Re: can anyone tell me how this is working

Posted: Sat Nov 16, 2013 11:25 am
by cutedrummerboy
already 61 view but no one post any reply. can anyone explain me why that outbound interface configured like this??

Re: can anyone tell me how this is working

Posted: Sat Nov 16, 2013 2:07 pm
by cutedrummerboy
here is the more precise picture of that configuration...

Image

can any one explain why the red circled interface aka wan interface configured like this?

Re: can anyone tell me how this is working

Posted: Sun Nov 17, 2013 12:36 am
by Sob
It's point to point addressing (/32 netmask). Instead of using traditional subnet for the link, which would require at least four addresses (network, device A, device B and broadcast for /30), you can do it with just two. Device A gets one and you tell it the second one is on the other side of the link. And the other way around. And it works.

Reusing the address from subnet on the other interface is not necessary part of it. But as you see, it can be done. They probably felt really strong need to save addresses.

Also the screenshot is from some older RouterOS, current one no longer has broadcast field. But that doesn't really change anything.

Re: can anyone tell me how this is working

Posted: Sun Nov 17, 2013 10:08 am
by cutedrummerboy
ok thank you sob. now its clear to me.